1. Field of the Invention
The present invention relates to a fuel injection valve.
2. Description of Related Art
In a known fuel injection valve, an urging member is provided on a valve seat side of a movable core, through which a needle is received, to improve a response of the needle. In Japanese Unexamined Patent Publication JP2009-150346A (corresponding to US20090159729A1), the movable core is provided on a side of a flange of the needle, which is on the valve seat side. A first urging member, which urges the needle and the movable core in a valve closing direction toward a fuel injection hole, is provided on an opposite side of the flange of the needle, which is opposite from the valve seat. A second urging member, which urges the movable core and the needle in a valve opening direction, is provided on the valve seat side of the movable core. In such a fuel injection valve, the movable core is urged back by the second urging member upon compression of the second urging member by the movable core to possibly cause collision of the movable core against the flange of the needle, which is held in a valve closed state for closing the fuel injection hole with the needle. This collision of the movable core against the flange of the needle may possibly cause lifting of the needle away from the fuel injection hole to cause undesirable secondary valve opening of the injection hole.
Furthermore, Japanese Unexamined Patent publication JP2008-506875A (corresponding to US2008/0277505A1) teaches another fuel injection valve, in which an acceleration distance (prestrike gap) is provided between a movable core (armature) and a first flange (a flange of a needle). However, in this fuel injection valve, the first flange and a second flange need to be welded to the needle, and a sleeve needs to be welded to the movable core. Therefore, the number of components and the welding spots are disadvantageously increased, and the assembling of the fuel injection valve becomes more complicated. Furthermore, the welded portion between the first flange and the needle may possible be influenced by, for example, thermal deformation to possibly cause a change in the acceleration distance.